Air-conditioning device and air-conditioning system

ABSTRACT

Provided is an air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device including a heating means provided to the compressor, and configured to heat refrigerant in the compressor, and a controller configured to control the heating means. The controller includes a heat load learning unit configured to learn a heat load based on temperature data and air conditioning data, a stagnation prevention control start timing estimation unit configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and a device control unit configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.

TECHNICAL FIELD

The present disclosure relates to an air-conditioning device and an air-conditioning system that perform indoor air conditioning.

BACKGROUND ART

In some air-conditioning device that includes a refrigerant circuit, a compressor has been often provided to an outdoor unit. In such a case, if the air-conditioning device stops in an environment where the outside air temperature is low, a phenomenon called “stagnation” may occur where refrigerant condenses and stagnates in the compressor and a heat exchanger provided to the outdoor unit. In particular, in the case where refrigerant stagnates in the compressor, refrigerating machine oil in the compressor is diluted and hence, there is a possibility that malfunction occurs, such as seizure of the shaft of the compressor.

As a typical method for reducing stagnation of refrigerant in the compressor, there is a known technique where, during a period in which the operation of the compressor is stopped, refrigerant in the compressor is caused to evaporate by heating the compressor by a heater or by performing a stagnation prevention control referred to as a constraint energization control. The constraint energization control is a control of energizing a motor winding to heat the compressor without driving a motor in the compressor. Patent Literature 1 discloses a method where the amount of energization of a heater or the voltage of the constraint energization control is adjusted depending on the outside air temperature to reduce power consumption at the time of heating the compressor to cause refrigerant in the compressor to evaporate.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Unexamined Patent Application     Publication No. 7-167504

SUMMARY OF INVENTION Technical Problem

However, in some air-conditioning device, when to start the operation cannot be determined during a period in which the operation of the compressor is stopped and hence, the stagnation prevention control is always performed. Accordingly, there is a problem in that power consumption increases during the period in which the operation of the compressor is stopped.

The present disclosure has been made in view of the above-mentioned problem of the known technique, and it is an objective of the present disclosure to provide an air-conditioning device and an air-conditioning system that can reduce power consumption during a period in which the operation of the compressor is stopped.

Solution to Problem

An air-conditioning device according to one embodiment of the present disclosure is an air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device including a heating means provided to the compressor, and configured to heat refrigerant in the compressor, and a controller configured to control the heating means. The controller includes a heat load learning unit configured to learn a heat load based on temperature data and air conditioning data, a stagnation prevention control start timing estimation unit configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and a device control unit configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.

An air-conditioning device according to another embodiment of the present disclosure is an air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device including a heating means provided to the compressor, and configured to heat refrigerant in the compressor, and a controller configured to control the heating means. The controller includes an outside air temperature learning unit configured to learn an outside air temperature for a set time interval based on a current outside air temperature, a stagnation prevention control required time period calculation unit configured to calculate, based on the outside air temperature obtained by learning, a stagnation prevention control required time period indicating a time period required for a stagnation prevention control of heating the compressor, and a device control unit configured to derive, based on a set time and the stagnation prevention control required time period, a stagnation prevention control start timing at which the stagnation prevention control is started, and configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing derived for the stagnation prevention control required time period calculated.

An air-conditioning system according to still another embodiment of the present disclosure is an air-conditioning system including at least one air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, and a management device configured to manage the at least one air-conditioning device. The at least one air-conditioning device includes a heating means provided to the compressor, and configured to heat refrigerant in the compressor, the management device includes a controller configured to control the heating means, and the controller includes a heat load learning unit configured to learn a heat load based on temperature data and air conditioning data, a stagnation prevention control start timing estimation unit configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and a device control unit configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.

An air-conditioning system according to yet another embodiment of the present disclosure is an air-conditioning system including at least one air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, and a management device configured to manage the at least one air-conditioning device. The at least one air-conditioning device includes a heating means provided to the compressor, and configured to heat refrigerant in the compressor, the management device includes a controller configured to control the heating means, and the controller includes an outside air temperature learning unit configured to learn an outside air temperature for a set time interval based on a current outside air temperature, a stagnation prevention control required time period calculation unit configured to calculate, based on the outside air temperature obtained by learning, a stagnation prevention control required time period indicating a time period required for a stagnation prevention control of heating the compressor, and a device control unit configured to derive, based on a set time and the stagnation prevention control required time period, a stagnation prevention control start timing at which the stagnation prevention control is started, and configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing derived for the stagnation prevention control required time period calculated.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, the stagnation prevention control is started at the estimated stagnation prevention control start timing and hence, the stagnation prevention control is performed appropriately. Accordingly, power consumption can be reduced during a period in which the operation of the compressor is stopped.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram showing one example of a configuration of an air-conditioning device according to Embodiment 1.

FIG. 2 is a function block diagram showing one example of a configuration of a controller shown in FIG. 1.

FIG. 3 is a hardware configuration diagram showing one example of the configuration of the controller shown in FIG. 2.

FIG. 4 is a hardware configuration diagram showing another example of the configuration of the controller shown in FIG. 2.

FIG. 5 is a schematic view showing one example of a model of machine learning performed by a heat load learning unit shown in FIG. 2.

FIG. 6 is a flowchart showing one example of a flow of learning performed by the heat load learning unit shown in FIG. 2.

FIG. 7 is a flowchart showing one example of a flow of stagnation prevention control performed by the air-conditioning device according to Embodiment 1.

FIG. 8 is a function block diagram showing one example of a configuration of a controller according to Embodiment 2.

FIG. 9 is a flowchart showing one example of a flow of learning performed by an outside air temperature learning unit shown in FIG. 8.

FIG. 10 is a flowchart showing one example of a flow of stagnation prevention control performed by an air-conditioning device according to Embodiment 2.

FIG. 11 is a circuit diagram showing one example of a configuration of an air-conditioning system according to Embodiment 3.

DESCRIPTION OF EMBODIMENTS

Hereinafter, Embodiments of the present disclosure will be described with reference to drawings. The present disclosure is not limited to the following Embodiments, and various modifications are possible without departing from the gist of the present disclosure. Further, the present disclosure includes any combination of the configurations that can be obtained by combining configurations shown in the following respective Embodiments. In the respective drawings, components given the same reference signs are identical or corresponding components, and the reference signs are common in the entire description.

Embodiment 1

An air-conditioning device according to Embodiment 1 will be described. The air-conditioning device according to Embodiment 1 performs air conditioning of an air-conditioned space by causing refrigerant to cycle through a refrigerant circuit.

[Configuration of Air-Conditioning Device 1]

FIG. 1 is a circuit diagram showing one example of a configuration of the air-conditioning device according to Embodiment 1. As shown in FIG. 1, an air-conditioning device 1 includes an outdoor unit 10, an indoor unit 20, and a controller 30. The outdoor unit 10 and the indoor unit 20 are connected with each other via refrigerant pipes.

The outdoor unit 10 includes a compressor 11, a refrigerant flow passage switching device 12, an outdoor heat exchanger 13, an expansion valve 14, and an outside air temperature sensor 15. The indoor unit 20 includes an indoor heat exchanger 21 and an indoor temperature sensor 22. In the air-conditioning device 1, the compressor 11, the refrigerant flow passage switching device 12, the outdoor heat exchanger 13, the expansion valve 14, and the indoor heat exchanger 21 are sequentially connected via refrigerant pipes to form the refrigerant circuit through which refrigerant cycles.

(Outdoor Unit 10)

The compressor 11 suctions refrigerant of low temperature and low pressure, compresses the suctioned refrigerant into a high temperature and high pressure state, and then discharges the refrigerant. The compressor 11 is an inverter compressor where capacity, which is the delivery amount per unit time, is controlled by changing the operating frequency. The operating frequency of the compressor 11 is controlled by the controller 30.

The refrigerant flow passage switching device 12 is a four-way valve, for example. The refrigerant flow passage switching device 12 switches between a cooling operation and a heating operation by switching flow directions of refrigerant. During the cooling operation, the refrigerant flow passage switching device 12 is switched to a state shown by solid lines in FIG. 1, that is, a state where the discharge port of the compressor 11 and the outdoor heat exchanger 13 are connected. During the heating operation, the refrigerant flow passage switching device 12 is switched to a state shown by broken lines in FIG. 1, that is, a state where the suction port of the compressor 11 and the outdoor heat exchanger 13 are connected. Switching of flow passages performed by the refrigerant flow passage switching device 12 is controlled by the controller 30.

The outdoor heat exchanger 13 is a fin-and-tube heat exchanger, for example. The outdoor heat exchanger 13 exchanges heat between refrigerant and outdoor air supplied by a fan or other similar device not shown in the drawing. During the cooling operation, the outdoor heat exchanger 13 is used as a condenser that rejects heat of refrigerant to outdoor air to condense the refrigerant. During the heating operation, the outdoor heat exchanger 13 is used as an evaporator that evaporates refrigerant to cool outdoor air by the heat of vaporization from the evaporation of the refrigerant.

The expansion valve 14 causes refrigerant to expand by reducing the pressure of the refrigerant. The expansion valve 14 is a valve whose opening degree can be controlled, such as an electronic expansion valve, for example. The opening degree of the expansion valve 14 is controlled by the controller 30. The outside air temperature sensor 15 is provided in the vicinity of the outdoor heat exchanger 13 to detect outside air temperature. The outside air temperature detected by the outside air temperature sensor 15 is supplied to the controller 30.

In Embodiment 1, a heating means 16 is provided to the compressor 11. With the control from the controller 30, the heating means 16 heats and evaporates refrigerant having stagnated in the compressor 11 during a period in which the compressor 11 is stopped.

Specifically, a heater attached to the periphery of the compressor 11, such as a belt heater, is used as the heating means 16, for example. When the heater is energized by a control from the controller 30, the compressor 11 is heated. To perform a constraint energization control, the heating means 16 may also be, for example, an energization control device that controls energization of the compressor 11. The constraint energization control is a control where any two phases of three phases of power supplied to the compressor 11 are intermittently energized to heat the compressor 11 without driving a motor in the compressor 11.

(Indoor Unit 20)

The indoor heat exchanger 21 exchanges heat between refrigerant and indoor air supplied by a fan or other similar device not shown in the drawing. With such heat exchange, cooling air or heating air to be supplied to an indoor space is generated. During the cooling operation, the indoor heat exchanger 21 is used as an evaporator, and cools the air-conditioned space by cooling the air of the air-conditioned space. During the heating operation, the indoor heat exchanger 21 is used as a condenser, and heats the air-conditioned space by heating the air of the air-conditioned space.

The indoor temperature sensor 22 is provided in the vicinity of the indoor heat exchanger 21 to detect temperature of indoor air. The indoor temperature detected by the indoor temperature sensor 22 is supplied to the controller 30.

(Controller 30)

The controller 30 controls separate units provided to the outdoor unit 10 and separate units provided to the indoor unit 20. In particular, in Embodiment 1, based on data including, for example, the outside air temperature detected by the outside air temperature sensor 15 and the indoor temperature detected by the indoor temperature sensor 22, the controller 30 controls the heating means 16 for the compressor 11 to perform stagnation prevention control. The stagnation prevention control is a control of causing refrigerant having stagnated in the compressor 11 to evaporate by the heating means 16 provided to the compressor 11.

FIG. 2 is a function block diagram showing one example of a configuration of the controller shown in FIG. 1. As shown in FIG. 2, the controller 30 includes a data acquisition unit 31, a heat load learning unit 32, a stagnation prevention control start timing estimation unit 33, a device control unit 34, and a data holding unit 35. The controller 30, for example, is an arithmetic device, such as a microcomputer, that implements various functions by executing software, or is hardware, such as a circuit device, that corresponds to the various functions. In FIG. 2, only components for functions relating to Embodiment 1 are illustrated, and the illustration of the other components will be omitted.

The data acquisition unit 31 acquires various pieces of data. Specifically, the data acquisition unit 31 acquires outside air temperature detected by the outside air temperature sensor 15 and indoor temperature detected by the indoor temperature sensor 22 as temperature data. The data acquisition unit 31 also acquires set temperature set for the indoor unit 20 by a user or other person and operating frequency of the compressor 11 as air conditioning data. The data acquisition unit 31 supplies the acquired temperature data and the acquired air conditioning data to the data holding unit 35.

The heat load learning unit 32 learns the heat load of the air-conditioning device 1 by machine learning by using various pieces of data, such as temperature data and air conditioning data that are held in the data holding unit 35. Specifically, the heat load learning unit 32 learns an amount of heat processed by the air-conditioning device 1 from current time, outside air temperature, indoor temperature, set temperature, and operating frequency of the compressor 11, for example. In Embodiment 1, the air-conditioning device 1 has only the amount of heat processed by the air-conditioning device 1 as data relating to heat load. In such a case where an amount of heat is thought to be equal to the heat load in an air-conditioned space, the air-conditioning device 1 can obtain the heat load of the air-conditioned space. Accordingly, the heat load learning unit 32 relatively learns the heat load of the air-conditioned space by learning the amount of heat processed by the air-conditioning device 1. Learning of the heat load will be described later. The heat load learning unit 32 also derives the heat load based on temperature data and air conditioning data by using the learning results obtained as described above.

The stagnation prevention control start timing estimation unit 33 estimates, based on the heat load obtained by learning by the heat load learning unit 32, a stagnation prevention control start timing by using an estimation means, such as a timing estimation formula set in advance. The stagnation prevention control start timing is a timing at which the stagnation prevention control is started. To allow the indoor temperature to reach a set temperature at a set time, such as an operation start time set by a user, the stagnation prevention control start timing is a time prior to a start-up time at which the air-conditioning device 1 is caused to start up.

The device control unit 34 generates and outputs a stagnation prevention command signal for controlling the heating means 16 at the estimated stagnation prevention control start timing based on the estimation result from the stagnation prevention control start timing estimation unit 33.

The data holding unit 35 holds various pieces of information used by the separate units of the controller 30. In Embodiment 1, for example, the data holding unit 35 holds various pieces of data including the temperature data and the air conditioning data that are acquired by the data acquisition unit 31 and that are used when learning is performed by the heat load learning unit 32.

FIG. 3 is a hardware configuration diagram showing one example of the configuration of the controller shown in FIG. 2. In the case where the various functions of the controller 30 are executed by hardware, as shown in FIG. 3, the controller 30 shown in FIG. 2 is a processing circuit 41. In the controller 30 shown in FIG. 2, the respective functions of the data acquisition unit 31, the heat load learning unit 32, the stagnation prevention control start timing estimation unit 33, the device control unit 34, and the data holding unit 35 are implemented by the processing circuit 41.

In the case where the respective functions are executed by hardware, for example, the processing circuit 41 corresponds to a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of the above. The controller 30 may implement each of the functions of the respective units, that is, the data acquisition unit 31, the heat load learning unit 32, the stagnation prevention control start timing estimation unit 33, the device control unit 34, and the data holding unit 35, by the processing circuit 41, or may implement the functions of the respective units by one processing circuit 41.

FIG. 4 is a hardware configuration diagram showing another example of the configuration of the controller shown in FIG. 2. In the case where the various functions of the controller 30 are executed by software, as shown in FIG. 4, the controller 30 shown in FIG. 2 includes a processor 51 and a memory 52. In the controller 30, the respective functions of the data acquisition unit 31, the heat load learning unit 32, the stagnation prevention control start timing estimation unit 33, the device control unit 34, and the data holding unit 35 are implemented by the processor 51 and the memory 52.

In the case where the respective functions are executed by software, in the controller 30, the functions of the data acquisition unit 31, the heat load learning unit 32, the stagnation prevention control start timing estimation unit 33, the device control unit 34, and the data holding unit 35 are implemented by software, firmware, or the combination of the software and the firmware. The software or the firmware is described as a program, and is stored in the memory 52. The processor 51 reads and executes the program stored in the memory 52 to implement the functions of the respective units.

As the memory 52, for example, a nonvolatile or volatile semiconductor memory is used, such as a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable and programmable ROM (EPROM), and an electrically erasable and programmable ROM (EEPROM). Further, as the memory 52, for example, a detachable recording medium may be used, such as a magnetic disk, a flexible disk, an optical disc, a compact disc (CD), a mini disc (MD), and a digital versatile disc (DVD).

[Action of Air-Conditioning Device 1]

Next, the action of the air-conditioning device 1 having such a configuration will be described together with the flow of refrigerant with reference to FIG. 1. In FIG. 1, solid lines show a state of the refrigerant flow passage switching device 12 when the air-conditioning device 1 performs the heating operation. The air-conditioning device 1 can perform both the cooling operation and the heating operation. However, in Embodiment 1, the action of the air-conditioning device 1 during the heating operation will be described, and the description for the action of the air-conditioning device 1 during the cooling operation will be omitted.

(During Heating Operation)

A case where the air-conditioning device 1 performs the heating operation will be described. When the compressor 11 is driven, refrigerant in a gas state at high temperature and high pressure is discharged from the compressor 11. The gas refrigerant of high temperature and high pressure discharged from the compressor 11 flows into the indoor heat exchanger 21, which is used as a condenser, via the refrigerant flow passage switching device 12. In the indoor heat exchanger 21, heat exchange is performed between the gas refrigerant of high temperature and high pressure that flows into the indoor heat exchanger 21 and indoor air supplied by an air-sending device not shown in the drawing. With such heat exchange, the gas refrigerant of high temperature and high pressure is condensed, thus becoming high-pressure liquid refrigerant.

The high-pressure liquid refrigerant that flows out from the indoor heat exchanger 21 expands in the expansion valve 14, thus becoming refrigerant in a two-phase state where low-pressure gas refrigerant and low-pressure liquid refrigerant are in a mixed state. The refrigerant in a two-phase state flows into the outdoor heat exchanger 13, which is used as an evaporator. In the outdoor heat exchanger 13, heat exchange is performed between the refrigerant in a two-phase state that flows into the outdoor heat exchanger 13 and outdoor air supplied by an air-sending device not shown in the drawing. With such heat exchange, liquid refrigerant evaporates from the refrigerant in a two-phase state, so that the refrigerant becomes low-pressure gas refrigerant. The low-pressure gas refrigerant that flows out from the outdoor heat exchanger 13 flows into the compressor 11 via the refrigerant flow passage switching device 12, and is compressed, thus becoming gas refrigerant of high temperature and high pressure. Then, the gas refrigerant is discharged from the compressor 11 again. Hereinafter, this cycle is repeated.

[Stagnation Prevention Control]

Next, the stagnation prevention control performed by the air-conditioning device 1 according to Embodiment 1 will be described. In a typical air-conditioning device, operation schedule, such as an operation start time and an operation stop time can be set in advance by a user. In this case, to allow the indoor temperature to reach a set temperature at the set time that is set in advance, it is necessary to start up the air-conditioning device at a start-up time prior to the set time.

During a period in which the operation of the air-conditioning device is stopped, as also described in Background Art, “stagnation” may occur where refrigerant condenses and stagnates in the compressor. Therefore, even when the air-conditioning device starts up at the start-up time in a state of stagnation occurring, the compressor is not normally activated and hence, it is difficult to allow the indoor temperature to reach the set temperature at the set time.

In view of the above, in the air-conditioning device 1 according to Embodiment 1, a stagnation prevention control start timing, at which stagnation prevention control is started, is estimated such that the air-conditioning device 1 starts up at a start-up time prior to the set time set by a user in a state where stagnation is eliminated. The air-conditioning device 1 starts the stagnation prevention control at the estimated stagnation prevention control start timing.

In estimating the stagnation prevention control start timing, a heat load processed by the air-conditioning device 1 is used. To acquire such a heat load, in Embodiment 1, learning of the heat load is performed by the heat load learning unit 32 of the controller 30.

(Learning of Heat Load)

Learning of a heat load performed by the heat load learning unit 32 will be described. To acquire a heat load used in estimating a start timing for the stagnation prevention control by the stagnation prevention control start timing estimation unit 33, the heat load learning unit 32 performs learning of a heat load processed by the air-conditioning device 1. Machine learning is used for learning a heat load.

FIG. 5 is a schematic view showing one example of a model of machine learning performed by the heat load learning unit shown in FIG. 2. In the machine learning model shown in FIG. 5, preprocessing is performed on input data. A heat load is estimated from the data, on which preprocessing is performed, by using a learning model, and the heat load is output.

In this case, outside air temperature, indoor temperature, set temperature, and action capability, for example, are used for input data. Temperature data detected by the outside air temperature sensor 15 is used for the outside air temperature. Temperature data detected by the indoor temperature sensor 22 is used for the indoor temperature. The set temperature is a temperature set for the indoor unit 20, and air conditioning data held in the data holding unit 35 is used for the set temperature. The action capability may be operating frequency of the compressor 11, for example, and air conditioning data held in the data holding unit 35 is used for the action capability. For alternative data for the outside air temperature or the indoor temperature, data from the weather forecast, for example, may be used.

In the preprocessing, processing set in advance, such as optimization of input data and reduction in input dimensions, is performed. More specifically, in the case where temperature data is input as input data, in the preprocessing, for example, processing set in advance, such as derivation of a differential value between a set temperature and an indoor temperature and normalization, is performed on the input data.

The learning model may be, for example, a heat load calculation formula that derives a heat load as output data that correspond to input data. The learning model is formed by using learning with a teacher, for example. An example of the learning model is not limited to the above, and a neural network, deep learning, or other similar technique may be used depending on the required accuracy and computational capacity.

Each time a plurality of data are input, parameters included in the heat load calculation formula of the learning model are updated. Specifically, for example, in the case where the learning model is formed by learning with a teacher, the learning model outputs output data by using the heat load calculation formula based on input data. The output data is input in an evaluation function together with teacher data. The evaluation function evaluates validity of the heat load calculation formula, which is the learning model, based on the output data and the teacher data. Then, the heat load learning unit 32 updates the parameters of the heat load calculation formula such that the output data calculated from the heat load calculation formula approach the teacher data.

FIG. 6 is a flowchart showing one example of a flow of learning performed by the heat load learning unit shown in FIG. 2. In step S1, the data acquisition unit 31 of the controller 30 acquires an outside air temperature detected by the outside air temperature sensor 15 and an indoor temperature detected by the indoor temperature sensor 22 as temperature data. The acquired temperature data are held in the data holding unit 35. In step S2, the data acquisition unit 31 acquires a set temperature set for the indoor unit 20 and operating frequency of the compressor 11 as air conditioning data. The acquired air conditioning data are held in the data holding unit 35.

In step S3, the heat load learning unit 32 determines whether it is a learning timing. The learning timing here is determined to be set to an arbitrary timing set in advance. When it is the learning timing (YES in step S3), the heat load learning unit 32 performs learning of the heat load of the air-conditioning device 1 by using the temperature data and the air conditioning data that are held in the data holding unit 35. In contrast, when it is not the learning timing (NO in step S3), the process returns to step S1. Hereinafter, processing in step S1 to step S4 is cyclically repeated with a fixed period.

(Estimation of Start Timing for Stagnation Prevention Control)

Next, estimation of a start timing for the stagnation prevention control performed by the stagnation prevention control start timing estimation unit 33 will be described. The stagnation prevention control start timing estimation unit 33 estimates, by using the heat load derived by the heat load learning unit 32, a timing at which the stagnation prevention control, which is performed prior to a start-up time, is started. For example, the stagnation prevention control start timing estimation unit 33 estimates the stagnation prevention control start timing such that the higher the derived heat load is, the earlier the stagnation prevention control is started.

(Stagnation Prevention Control)

FIG. 7 is a flowchart showing one example of a flow of the stagnation prevention control performed by the air-conditioning device according to Embodiment 1. In step S11, the data acquisition unit 31 acquires the outside air temperature detected by the outside air temperature sensor 15 and the indoor temperature detected by the indoor temperature sensor 22 as temperature data. The acquired temperature data are supplied to the heat load learning unit 32, and are held in the data holding unit 35. In step S12, the data acquisition unit 31 acquires, as air conditioning data, a set temperature and an operation start time that are set for the indoor unit 20 and action capability, such as the operating frequency of the compressor 11. The acquired air conditioning data are supplied to the heat load learning unit 32, and are held in the data holding unit 35. Processing in step S11 and step S12 is performed arbitrary time period prior to the set time, such as the operation start time.

When the temperature data and the air conditioning data are input, the heat load learning unit 32 derives a heat load in step S13. In step S14, the stagnation prevention control start timing estimation unit 33 estimates a stagnation prevention control start timing by using an estimation means, such as a timing estimation formula, based on the heat load derived in step S13. At this point of operation, the stagnation prevention control start timing estimation unit 33 estimates the stagnation prevention control start timing such that the higher the heat load is, the earlier the stagnation prevention control is started.

In step S15, the device control unit 34 determines whether it is a time indicated by the stagnation prevention control start timing. When it is the stagnation prevention control start timing (YES in step S15), the device control unit 34 generates a stagnation prevention command signal and outputs the stagnation prevention command signal to the heating means 16 in step S16. The stagnation prevention control is performed by the heating means 16 in this manner. In this case, the stagnation prevention control is performed for a fixed time period that is fixedly set.

In contrast, when it is not the stagnation prevention control start timing (NO in step S15), the process returns to step S15, and the processing in step S15 is repeated until the stagnation prevention control start timing is reached.

As described above, the air-conditioning device 1 according to Embodiment 1 learns a heat load based on temperature data and air conditioning data, and estimates a stagnation prevention control start timing based on the heat load obtained by learning. Then, the air-conditioning device 1 performs the stagnation prevention control of heating the compressor 11 at the estimated stagnation prevention control start timing.

In the air-conditioning device 1, the stagnation prevention control is started at the estimated stagnation prevention control start timing in this manner and hence, unlike a known technique, there is no possibility that the stagnation prevention control is always performed during a period in which the operation of the compressor 11 is stopped. Therefore, it is possible to reduce power consumption during a period in which the operation of the compressor 11 is stopped.

At this point of operation, the controller 30 acquires the outside air temperature detected by the outside air temperature sensor 15 and the indoor temperature detected by the indoor temperature sensor 22 as temperature data. The controller 30 also acquires the operating frequency of the compressor 11 as air conditioning data. The controller 30 may acquire the set temperature set for the indoor unit 20 as air conditioning data.

In the air-conditioning device 1 according to Embodiment 1, a heater attached to the periphery of the compressor 11 may be used for the heating means 16. With such a configuration, when the stagnation prevention control is performed, the heater is energized, thus heating the compressor 11.

An energization control device that controls energization of the compressor 11 may also be used for the heating means 16. With such a configuration, when the stagnation prevention control is performed, the compressor 11 is energized such that the constraint energization control is performed and hence, the compressor 11 can be heated.

Embodiment 2

Next, Embodiment 2 will be described. Embodiment 2 differs from Embodiment 1 in that the time period required for the stagnation prevention control is calculated. In Embodiment 2, components identical to the corresponding components in Embodiment 1 are given the same reference signs, and the detailed description of such components will be omitted.

An air-conditioning device 1 according to Embodiment 2 is substantially equal to the air-conditioning device 1 according to Embodiment 1 shown in FIG. 1 except for the configuration of the controller 30 and hence, the detailed description of the air-conditioning device 1 according to Embodiment 2 will be omitted.

[Configuration of Controller 30]

In the same manner as Embodiment 1, the controller 30 controls separate units provided to the outdoor unit 10 and separate units provided to the indoor unit 20. In Embodiment 2, in addition to the functions of the controller 30 according to Embodiment 1, the controller 30 estimates outside air temperatures for set time intervals, set in advance, based on the outside air temperature detected by the outside air temperature sensor 15, and calculates the time period required for the stagnation prevention control based on the estimation result.

FIG. 8 is a function block diagram showing one example of a configuration of the controller according to Embodiment 2. As shown in FIG. 8, the controller 30 includes the data acquisition unit 31, the device control unit 34, the data holding unit 35, an outside air temperature learning unit 36, and a stagnation prevention control required time period calculation unit 37. The controller 30 may be, for example, an arithmetic device, such as a microcomputer, that implements various functions by executing software, or may be hardware, such as a circuit device, that corresponds to the various functions. In FIG. 8, only components having functions relating to Embodiment 2 are illustrated, and the illustration of the other components will be omitted.

The outside air temperature learning unit 36 learns outside air temperatures for the set time intervals by machine learning by using the outside air temperature included in temperature data held in the data holding unit 35. Learning of outside air temperature will be described later in detail. Further, the outside air temperature learning unit 36 derives, by using the above-mentioned learning results, the outside air temperatures for the set time intervals based on a current outside air temperature detected by the outside air temperature sensor 15.

The stagnation prevention control required time period calculation unit 37 calculates a stagnation prevention control required time period based on the outside air temperatures obtained by learning by the outside air temperature learning unit 36. The stagnation prevention control required time period is the minimum time period required for the stagnation prevention control to evaporate refrigerant in the compressor 11. The stagnation prevention control required time period calculation unit 37 calculates a stagnation prevention control required time period by using a predetermined calculation formula based on the current outside air temperature and the outside air temperatures for the set time intervals obtained by learning.

Based on the calculation result from the stagnation prevention control required time period calculation unit 37, the device control unit 34 derives a start timing for the stagnation prevention control from a set time and the stagnation prevention control required time period such that the stagnation prevention control is performed for the stagnation prevention control required time period. Then, the device control unit 34 generates and outputs a stagnation prevention command signal. In Embodiment 2, the stagnation prevention command signal includes information indicating a start timing for the stagnation prevention control and information indicating an execution time period for the stagnation prevention control.

In the same manner as Embodiment 1, the data holding unit 35 holds various pieces of information used by the separate units of the controller 30. In Embodiment 2, for example, the data holding unit 35 holds various pieces of data including the temperature data and the air conditioning data that are acquired by the data acquisition unit 31 and that are used when learning is performed by the heat load learning unit 32 and the outside air temperature learning unit 36.

[Stagnation Prevention Control]

Next, the stagnation prevention control performed by the air-conditioning device 1 according to Embodiment 2 will be described. In the case where stagnation of refrigerant occurs in the compressor 11, the amount of refrigerant condensed varies with the outside air temperature. Therefore, the time period required for the stagnation prevention control of heating refrigerant in the compressor 11 varies with the outside air temperature.

In this case, if a time period during which the stagnation prevention control is performed is fixedly determined, there is a possibility that the stagnation prevention control is not performed for an appropriate time period depending on the degree of stagnation. For example, in the case where the amount of condensed refrigerant is relatively large, it is necessary to set a long time period for the stagnation prevention control. In contrast, in the case where the amount of condensed refrigerant is relatively small, it is sufficient to set a short time period for the stagnation prevention control.

In view of the above, in Embodiment 2, the stagnation prevention control required time period, which is a time period required for the stagnation prevention control, is calculated such that a stagnation prevention control time period during the stagnation prevention control is an appropriate time period depending on the state of stagnation. The air-conditioning device 1 performs the stagnation prevention control for the calculated stagnation prevention control required time period.

When the stagnation prevention control required time period is calculated, the outside air temperatures for the set time intervals are used. To obtain such outside air temperatures, in Embodiment 2, learning of outside air temperature is performed by the outside air temperature learning unit 36 of the controller 30.

(Learning of Outside Air Temperature)

Learning of outside air temperature performed by the outside air temperature learning unit 36 will be described. The outside air temperature learning unit 36 performs learning of outside air temperatures for the set time intervals to acquire outside air temperatures that are used for estimating a required time period for the stagnation prevention control by the stagnation prevention control required time period calculation unit 37. In the same manner as the heat load learning unit 32 in Embodiment 1, machine learning is used for the learning of outside air temperatures.

For a model of machine learning performed by the outside air temperature learning unit 36, a machine learning model shown in FIG. 5 is used. In this case, outside air temperature is used for input data, for example. As alternative data for outside air temperature, data from the weather forecast, for example, may be used.

FIG. 9 is a flowchart showing one example of a flow of learning performed by the outside air temperature learning unit shown in FIG. 8. In step S21, the data acquisition unit 31 of the controller 30 acquires an outside air temperature detected by the outside air temperature sensor 15 as temperature data. The acquired temperature data is held in the data holding unit 35.

In step S22, the outside air temperature learning unit 36 determines whether it is the learning timing. The learning timing here is determined to be set to an arbitrary timing set in advance. When it is the learning timing (YES in step S22), the outside air temperature learning unit 36 performs learning of outside air temperatures for the set time intervals by using temperature data held in the data holding unit 35. In contrast, when it is not the learning timing (NO in step S22), the process returns to step S21. Hereinafter, processing in step S21 to step S23 is cyclically repeated with a fixed period.

(Calculation of Required Time Period for Stagnation Prevention Control)

Next, calculation of the required time period for the stagnation prevention control performed by the stagnation prevention control required time period calculation unit 37 will be described. The stagnation prevention control required time period calculation unit 37 calculates a required time period for the stagnation prevention control by using the outside air temperatures derived by the outside air temperature learning unit 36. For example, the stagnation prevention control required time period calculation unit 37 calculates the stagnation prevention control required time period such that the higher the derived outside air temperatures are, the shorter an execution time period for the stagnation prevention control becomes.

(Stagnation Prevention Control)

FIG. 10 is a flowchart showing one example of a flow of the stagnation prevention control performed by the air-conditioning device according to Embodiment 2. In FIG. 10, processing that is common to processing for the stagnation prevention control in Embodiment 1 shown in FIG. 7 is given the same reference sign, and the repeated description of such processing will be omitted.

The data acquisition unit 31 acquires temperature data in step S11 and air conditioning data in step S12. The acquired temperature data and air conditioning data are supplied to the outside air temperature learning unit 36, and are held in the data holding unit 35.

After the temperature data are input, the outside air temperature learning unit 36 derives outside air temperatures for set time intervals in step S31. The outside air temperature learning unit 36 extracts an outside air temperature having the lowest temperature from the derived outside air temperatures for the set time intervals. In step S32, the stagnation prevention control required time period calculation unit 37 calculates a stagnation prevention control required time period based on the outside air temperature extracted in step S31 and the outside air temperature held in the data holding unit 35.

In step S15, the device control unit 34 determines whether it is the time indicated by the stagnation prevention control start timing. The stagnation prevention control start timing is derived by calculating backward from a start-up time by the calculated stagnation prevention control required time period. When it is the stagnation prevention control start timing (YES in step S15), the device control unit 34 generates a stagnation prevention command signal and outputs the stagnation prevention command signal to the heating means 16 in step S33. With such a configuration, the stagnation prevention control is performed by the heating means 16 for the stagnation prevention control required time period.

In contrast, when it is not the stagnation prevention control start timing (NO in step S15), the process returns to step S15, and the processing in step S15 is repeated until the stagnation prevention control start timing is reached.

As described above, in the air-conditioning device 1 according to Embodiment 2, the controller 30 learns outside air temperatures for the set time intervals based on outside air temperature, and calculates the stagnation prevention control required time period based on the outside air temperatures obtained by learning. The controller 30 derives the stagnation prevention control start timing based on a set time and the stagnation prevention control required time period. The controller 30 controls the heating means 16 such that the stagnation prevention control is performed at the derived stagnation prevention control start timing for the calculated stagnation prevention control required time period.

With such a configuration, in the same manner as Embodiment 1, it is possible to reduce power consumption during a period in which the operation of the compressor 11 is stopped. Further, in Embodiment 2, the time period required for the stagnation prevention control is calculated and hence, the stagnation prevention control is performed for an appropriate time period depending on the amount of refrigerant condensed in the compressor 11. Therefore, an unnecessary stagnation prevention control can be reduced and hence, power consumption can be reduced more appropriately during a period in which the operation of the compressor 11 is stopped.

Embodiment 3

Next, Embodiment 3 will be described. In Embodiment 3, the description will be made for an air-conditioning system where a function of the controller 30 that performs the stagnation prevention control is provided to a device different from the air-conditioning device. In Embodiment 3, components identical to the corresponding components in Embodiments 1 and 2 are given the same reference signs, and the detailed description of such components will be omitted.

[Configuration of Air-Conditioning System 100]

FIG. 11 is a circuit diagram showing one example of a configuration of the air-conditioning system according to Embodiment 3. As shown in FIG. 11, an air-conditioning system 100 includes one or a plurality of air-conditioning devices 110 and a management device 120 connected to each of the air-conditioning devices 110.

In the same manner as the air-conditioning device 1 of Embodiments 1 and 2 shown in FIG. 1, each air-conditioning device 110 includes the outdoor unit 10 and the indoor unit 20, and the outdoor unit 10 includes the compressor 11 to which the heating means 16 is provided. The air-conditioning device 110 has a configuration obtained by excluding the function of performing the stagnation prevention control from the controller 30 of the air-conditioning device 1 shown in FIG. 1.

The management device 120 manages the one or the plurality of air-conditioning devices 110 connected to the management device 120. In Embodiment 3, the management device 120 receives temperature data and air conditioning data from each of the air-conditioning devices 110, and performs the stagnation prevention control on the corresponding one of the air-conditioning devices 110 based on the received temperature data and air conditioning data.

The management device 120 includes a controller 130. The controller 130 has a function of performing the stagnation prevention control performed by the controller 30 shown in FIG. 1. That is, the controller 130 has a configuration substantially equal to the configuration of the controller 30 according to Embodiment 1 or 2.

In the case where the controller 130 has the configuration substantially equal to the configuration of the controller 30 according to Embodiment 1, as shown in FIG. 2, the controller 130 includes the data acquisition unit 31, the heat load learning unit 32, the stagnation prevention control start timing estimation unit 33, the device control unit 34, and the data holding unit 35. In the case where the controller 130 has a configuration substantially equal to the configuration of the controller 30 according to Embodiment 2, as shown in FIG. 8, the controller 130 includes the data acquisition unit 31, the heat load learning unit 32, the stagnation prevention control start timing estimation unit 33, the device control unit 34, the data holding unit 35, the outside air temperature learning unit 36, and the stagnation prevention control required time period calculation unit 37.

As described above, the air-conditioning system 100 according to Embodiment 3 has the configuration where the function of performing the stagnation prevention control for the air-conditioning device 1 described in Embodiments 1 and 2 is provided to the management device 120, which is different from the air-conditioning devices 110.

As described above, in the air-conditioning system 100 according to Embodiment 3, the controller 130 that performs the stagnation prevention control is provided to the management device 120 that manages the one or the plurality of air-conditioning devices 110. With such a configuration, in the same manner as Embodiments 1 and 2, it is possible to reduce power consumption during a period in which the operation of the compressor 11 of the air-conditioning device 110 is stopped. Further, in Embodiment 3, the controller 130 is provided separately from the air-conditioning devices 110 and hence, the stagnation prevention control can also be performed on an air-conditioning device that is already installed.

REFERENCE SIGNS LIST

1, 110: air-conditioning device, 10: outdoor unit, 11: compressor, 12: refrigerant flow passage switching device, 13: outdoor heat exchanger, 14: expansion valve, 15: outside air temperature sensor, 16: heating means, 20: indoor unit, 21: indoor heat exchanger, 22: indoor temperature sensor, 30, 130: controller, 31: data acquisition unit, 32: heat load learning unit, 33: stagnation prevention control start timing estimation unit, 34: device control unit, 35: data holding unit, 36: outside air temperature learning unit, 37: stagnation prevention control required time period calculation unit, 41: processing circuit, 51: processor, 52: memory, 100: air-conditioning system, 120: management device 

1. An air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device comprising: a heating means provided to the compressor, and configured to heat refrigerant in the compressor; and a controller configured to control the heating means, the controller being configured to learn a heat load based on temperature data and air conditioning data, configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.
 2. The air-conditioning device of claim 1, further comprising: an outside air temperature sensor configured to detect an outside air temperature; and an indoor temperature sensor configured to detect an indoor temperature, wherein the controller is configured to acquire, as the temperature data, the outside air temperature detected and the indoor temperature detected.
 3. The air-conditioning device of claim 1, wherein the controller is configured to acquire an operating frequency of the compressor as the air conditioning data.
 4. The air-conditioning device of claim 1, wherein the controller is configured to acquire, as the air conditioning data, a set temperature set for the indoor unit.
 5. An air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit, the air-conditioning device comprising: a heating means provided to the compressor, and configured to heat refrigerant in the compressor; and a controller configured to control the heating means, the controller being configured to learn an outside air temperature for a set time interval based on a current outside air temperature, configured to calculate, based on the outside air temperature obtained by learning, a stagnation prevention control required time period indicating a time period required for a stagnation prevention control of heating the compressor, and configured to derive, based on a set time and the stagnation prevention control required time period, a stagnation prevention control start timing at which the stagnation prevention control is started, and configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing derived for the stagnation prevention control required time period calculated.
 6. The air-conditioning device of claim 1, wherein the heating means is a heater attached to a periphery of the compressor.
 7. The air-conditioning device of claim 1, wherein the heating means is an energization control device configured to control energization of the compressor.
 8. An air-conditioning system comprising: at least one air-conditioning device that includes an outdoor unit and an indoor unit, the outdoor unit including a compressor, the indoor unit being connected to the outdoor unit; and a management device configured to manage the at least one air-conditioning device, the at least one air-conditioning device including a heating means provided to the compressor, and configured to heat refrigerant in the compressor, the management device including a controller configured to control the heating means, the controller being configured to learn a heat load based on temperature data and air conditioning data, configured to estimate a stagnation prevention control start timing based on the heat load obtained by learning, the stagnation prevention control start timing being a timing at which a stagnation prevention control of heating the compressor is started, and configured to control the heating means such that the stagnation prevention control is performed by the heating means at the stagnation prevention control start timing estimated.
 9. (canceled) 